Gas-assisted electrodeposition modulates the grain structure of Cu catalysts for selective conversion of CO2 to C2+ products

초록

Electrochemical CO2 reduction has attracted considerable research interest as a pathway to convert CO2 into value-added multicarbon products. Cu is a key catalyst for multicarbon-product formation, and its selectivity is strongly affected by its microstructure. However, the effect of the gas environment during electrodeposition on Cu growth and subsequent CO2 reduction performance remains poorly understood. Here, Cu catalysts were directly grown on a gas diffusion layer (GDL) in a flow-cell-based electrodeposition system while either CO2 or Ar was supplied to the backside of the GDL, allowing the gaseous growth environment to be varied during deposition. The electrodes prepared under backside CO2 supply exhibited finer surface features, and the representative Cu-gCO2−20 electrode showed a more highly subdivided crystallographic microstructure than the corresponding Ar-prepared electrode. These structural differences were associated with enhanced C2+ selectivity during subsequent CO2 reduction. Under representative operating conditions, the optimized electrode fabricated under CO2-supplied conditions achieved a C2+ Faradaic efficiency of approximately 70% and an FEC2+/FEC1 ratio of 5.5, compared with 2.7 for the corresponding Ar-prepared electrode. These findings highlight backside gas supply as an additional electrodeposition parameter for promoting the selective conversion and reuse of CO2 into multicarbon products, including ethylene and ethanol.

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